1. Field of the Invention
The present invention relates to a method for producing a chemically adsorbed film. More specifically, the present invention relates to a method for producing a chemically adsorbed film which may be provided as a monomolecular film on the surface of a polymer substrate and is useful in modifying the surface of the substrate.
2. Description of the Related Art
A conventional method for producing a chemically adsorbed film is disclosed, for example, in Japanese Patent Publication No. 5-16087. According to the method disclosed in the patent publication, a chemically adsorbed film is formed on the surface of a substrate by allowing hydrophilic groups such as hydroxyl groups on the surface of a substrate to react with a chlorosilane surfactant. In the case of using a substrate where a large number of hydrophilic groups such as hydroxyl groups do not exist on the surface of a substrate, the following method is known from Japanese Laid-Open Patent Publication No. 6-200074. For example, the surface of the substrate is oxidized so as to be hydrophilic; and then a chlorosilane surfactant is chemically adsorbed onto the surface by performing an oxygen plasma treatment, a corona treatment, a UV light irradiation using a low-pressure mercury lamp, an immersion of the substrate in a chromic acid mixture (a mixed solution of concentrated sulfuric acid and potassium bichromate), or the like.
According to these conventional methods, however, even when oxidization is performed, satisfactory effects cannot be obtained, and a sufficient amount of hydrophilic groups (e.g., hydroxyl groups) required for reacting with a chlorosilane surfactant cannot be produced on the surface of a substrate. As a result, a chemically adsorbed film cannot be formed on the surface of the substrate at all, and even if the film can be formed, a high-density chemically adsorbed film cannot be obtained because there are many pin holes in the resulting film. Therefore, neither a chemically adsorbed film having satisfactory properties, e.g., water repellency, oil repellency, anti-contaminating property, antistatic property and the like, nor a chemically adsorbed film having practical durability can be obtained.
In addition, according to the above-described methods, since a desired part of the surface of the substrate cannot be selectively oxidized, it is impossible to obtain a chemically adsorbed film on which desired fine patterns are formed.
Therefore, a method for producing a high-density chemically adsorbed film and a method for producing a chemically adsorbed film having desired fine patterns thereon are required to be developed.